Papers by Keyword: Tensile Failure

Abstract: In order to study the tensile failure of rock bridge, the finite element software which can simulate the cracking of pull and tensile stress was used to simulate the tensile failure process of rock bridge with multi-crack. The general finite element software can only simulation continuous medium, in this paper we succeeded in discontinuous problem with this finite element software. Reach a conclusion of the rupture results of rock bridge in rock mass with multi-crack under the conditions of uniaxial compression, and the law of the stress distribution in the process of destruction.

Abstract: Composite soil-nailing is a new technology developed from abroad in recent years, to be used in excavation of soil, slope stability. This paper studied the stress and deformation of composite soil nailing wall by nonlinear FEM. According to the structure characteristic, the finite element analysis for composite soil nailing construction process is carried out. Based on geotechnical elastic-plastic constitutive model, the adopted failure criterion was a composite Drucker-Prager criterion with tension cut-off. A kind of rotational Goodman interface element is employed to simulate the behavior of interface between the soil-mixed cement which forms the barrier of seepage flow along the boundary of foundation pit, and soil ground. Through the comparative analysis with on-site monitoring data, the finite element calculation results have good precision.

Abstract: For many quasi-brittle materials (such as rock, ceramic and concrete) in pure bending state, the material on the tensile side will fail firstly since the compressive strength can be ten times the tensile strength. After tensile strain localization zone is initiated in the midspan of the beam, its propagation direction will be perpendicular to the neutral axis. In the paper, using nonlocal theory or gradient-dependent plasticity, the distributions of local plastic tensile strain and local damage variable in tensile strain localization zone of a pure bending beam are analyzed theoretically. The evolutions of the maximum local plastic tensile strain, the maximum local damage variable and the bending moment with tensile stress acting on the tensile side are presented through examples. The distributions of local plastic tensile strain and local damage variable in tensile strain localization zone are highly nonuniform due to microstructural effect. When the maximum bending moment is reached, the maximum local damage variable is proportional to the ratio of elastic modulus to elastoplastic modulus, while the maximum local plastic tensile strain is inversely proportional to elastic modulus and elastoplastic modulus. For quasi-brittle materials, the elastoplastic modulus that is a constitutive parameter equal to the absolute value of the slope of tensile stress-tensile strain curve in strain-softening stage is much higher. The present theoretical results mean that the precursors to failure are less apparent for extremely brittle materials.

Abstract: A thorough investigation of the failure mechanisms of composite sandwich beams under four- and three-point bending and cantilever beams was undertaken. The beams were made of unidirectional carbon/epoxy (AS4/3501-6) facings and a PVC closed-cell foam (Divinycell) core. Two types of core material H100 and H250 with densities 100 and 250 kg/m3, respectively, were used. The failure modes investigated are face sheet compressive failure, core failure and facing wrinkling. The various modes have been studied separately and both initiation and ultimate failure have been determined. Initiation of a particular failure mode and triggering and interaction with other failure modes was also investigated.

Abstract: In the present paper, axisymmetric smooth and notched specimens of aluminium alloy LY12CZ were monotonic tension tested to study the ductile fracture behavior and evaluate the suitability for the critical void growth ratio, V_GC of the material, from the micro and macro points of view. It's found that the material would change fracture morphology from tensile to shear failure in the various stress states; the ductile fracture parameter V_GC is sensitive to the fracture morphology which is applicable for the case of tensile failure while not suitable for the case of the shear failure, i.e. the case of smooth tensile specimens.